Chronic kidney disease in dogs

Overview

What chronic means

Chronic kidney disease involves structural or functional abnormalities in one or both kidneys lasting over three months. Damage can exist early despite normal creatinine. Progressive failure accumulates substances normally excreted in urine.

Diagnosed prevalence in a UK primary care study was 0.21%. Estimated total prevalence was 0.37% after allowing for potentially undiagnosed cases. The study involved 89 practices.

Kidneys also regulate electrolytes and blood pressure. Effects elsewhere become more common from IRIS stage three onwards.

Causes

Kidney tissue damage

Glomeruli filter substances from blood into the initial filtrate. Damage can allow excess protein into urine. Tubular injury can also cause proteinuria. Persistent injury can scar kidney tissue. Greater scarring generally leaves poorer filtration.

Congenital structural abnormalities can initiate disease. Prolonged urinary obstruction can permanently damage tissue. Bacterial renal pelvis infection can acutely worsen existing disease. Advanced scarring does not always reveal the original cause.

After acute injury

Some acute kidney damage can remain permanent. One follow-up found chronic disease at three months in six treated dogs, or 25%. New acute injury can also occur with established chronic disease.

Among 132 survivors of acute kidney injury, creatinine normalised by discharge in 55%. It normalised later in a further 20%.

Risk factors

All ages can be affected, but disease is more common in older dogs. UK records retained an age association after accounting for other factors. Susceptibility has been identified in Cocker Spaniels and Cavalier King Charles Spaniels.

Cocker Spaniel familial nephropathy can emerge between six months and two years. It affects the basement membrane of glomerular filtration structures. A comparison of 117 affected and 137 control Boxers identified 21 associated genomic regions.

Cocker Spaniel familial nephropathy is recessively inherited.

Typical symptoms

Dogs can appear entirely healthy early on. Increased thirst and larger urine volumes are often the first home signs.

• The water bowl empties faster.
• More urine passes each time.
• Appetite falls with progression.
• Weight gradually decreases.
• Waste accumulation can cause vomiting.
• Dogs may tire more easily.
• Mouth ulcers can develop.

Advanced disease can cause dehydration despite previously heavy drinking. Chronic disease can reduce muscle mass. Anaemia can make gums pale.

Severe disease can also cause diarrhoea.

Complications and consequences

Phosphate, blood pressure and anaemia

Phosphate may initially remain normal because the body increases phosphorus elimination. It generally rises as function declines. Metabolic acidosis, acidification through metabolic disturbances, can occur. Hypertension can develop at any stage. It can damage the retina. Renal anaemia is usually non-regenerative: marrow does not produce enough replacement red cells.

Stage and prognosis

A UK primary care study found median time from diagnosis to kidney-related death of 226 days. A separate 27-dog follow-up found median survival from entry of around 14.78 months at IRIS stage two. Stage three had 11.14 months. Stage four had 1.98 months. Alongside stage, initial blood urea nitrogen was associated with survival in UK patients.

Muscle loss was associated with shorter survival in dogs with blood-test evidence of renal failure. High phosphate was also associated with greater death risk.

Diagnosis at the vet

Blood, urine and imaging

Creatinine and symmetric dimethylarginine, or SDMA, indicate filtration. Muscle loss can lower creatinine and mask deterioration. Dehydration can temporarily raise it. One raised creatinine or SDMA result cannot establish chronic disease. Uncertain borderline results can be repeated after around two weeks.

Urine specific gravity measures concentration. Culture alongside other findings can identify ascending infection. Ultrasound may show small, irregular kidneys. Early imaging can still look normal.

Research in northern Europe is investigating new markers for detecting and monitoring chronic injury. SDMA can rise before creatinine with only mild filtration loss. In one longitudinal follow-up, SDMA rose during early progression while other monitored values changed less.

IRIS staging and substaging

Staging follows confirmation of chronic disease. It uses at least two measurements in a stable, adequately hydrated dog. Stage one has creatinine below 125 µmol/l with other evidence of disease. Stage two is 125–250 µmol/l. Stage three is 251–440 µmol/l. Stage four exceeds 440 µmol/l. If creatinine and SDMA suggest different stages, tests can be repeated after two to four weeks.

Urine protein-to-creatinine ratio, or UPC, assesses proteinuria. Above 0.5 indicates proteinuria if inflammation or blood does not explain it. A canine UPC of 0.2–0.5 is borderline. Classification should ideally use at least two samples collected at least two weeks apart. Systolic pressure of 160–179 mmHg is hypertensive in most dogs. At least 180 mmHg indicates high organ injury risk.

Treatment

Renal diet and phosphate control

Treatment aims to slow functional decline. Symptom relief gains importance in advanced disease. Renal diets may be recommended from IRIS stage two. They contain less phosphorus than standard food. Protein is moderate and from high-quality sources.

Stage two phosphate targets are below 1.5 mmol/l. The lower target limit is 0.9 mmol/l. A practical stage three goal is below 1.6 mmol/l. Stage four aims below 1.9 mmol/l. Persistent elevation despite diet may require a phosphate binder. This reduces dietary phosphorus absorption. Calcium and phosphate are usually checked every four to six weeks initially.

In one 116-dog clinical study, renal diet-fed dogs lived longer than those eating other foods.

Blood pressure, proteinuria and anaemia

Antihypertensive treatment generally aims below 160 mmHg systolic. It can start promptly with established organ injury. Angiotensin receptor blockers can reduce urinary protein loss. Dehydration is corrected before starting them. Creatinine, electrolytes and blood pressure are monitored.

Renal anaemia is treated when haematocrit, the red cell volume fraction, is below 30%. Persistent renal anaemia at 30–35% also requires treatment. At stage two, a well-hydrated dog below 30% is first investigated for other anaemia causes.

Medication stimulating red cell production can be considered when renal anaemia needs treatment.

Hydration and adequate nutrition

Fluids can correct dehydration. Maropitant or ondansetron, for example, can relieve nausea and vomiting. Appetite medication may help dogs losing weight or muscle through poor intake. Feeding tubes can support inadequate food or fluid intake when other measures fail. Acidosis persisting despite renal diet may need prescribed medication correcting acid–base balance.

Prevention

After acute injury, kidney function is initially monitored at least every three months during the first year. Identifying obstruction or renal pelvis infection helps prevent further damage.

Some Cocker Spaniel breeding guidance recommends familial nephropathy genetic testing. At least one parent should be genetically clear to prevent affected puppies. Testing avoids risky pairings even when carriers look healthy.

The vet can withdraw nephrotoxic medication if considered feasible.

Important for dog owners

Keep fresh water available because diseased kidneys can lose concentrating ability. Record drinking, urination and appetite changes. Weigh regularly to detect gradual loss. Report all current medication. Nutritional assessment also considers muscle condition.

Wet food can provide more fluid than dry food. Monitor consumption alongside weight because disease can suppress appetite.

Frequently asked questions

Can kidney disease occur with normal creatinine?

Early disease can leave creatinine within range. Persistently raised SDMA or structural abnormalities can raise suspicion. Repeat tests assess stability or change. Ultrasound can also assess structure.

Can dogs drink heavily yet be dehydrated?

Yes, impaired concentration can cause substantial urinary water loss. Vomiting or inadequate drinking increases risk. Call an emergency clinic if water cannot be retained and condition worsens.

Does high creatinine always mean chronic disease?

Acute injury can also raise it. Dehydration can do so too. Assessment considers hydration, previous results and urine specific gravity. Sudden vomiting or rapid deterioration can suggest acute injury.

How long can an affected dog live?

Survival depends partly on stage at diagnosis. One follow-up found median survival of around 14.78 months at stage two. Stage four in the same follow-up had 1.98 months.

Why does dietary phosphorus matter?

Kidneys eliminate phosphorus, and phosphate can rise with progression. Renal diets reduce dietary intake. A binder can be added if diet alone fails to reach the stage-specific target.